Doom defined my childhood. I was lucky enough to have an older brother who was really into computers and knew how to get Doom multiplayer working over serial cables. I can remember being blown away by the first multiplayer FPS experience I'd ever had. Some of my best memories were spent fragging our friends while Rush or Dream Theater played in the background. The mods were amazing too. We would mess with the firing rate of the different weapons to create an entirely new experience. We found user created levels to play, too. Our favorite was a map entitled butt.wad (wow, I only just now got that joke) which had the Marriage of Figaro playing in the background. I even got into modding myself, creating maps and re-skinning characters in the game. Man those were good times.